1. Field of the Invention
The invention relates to a connector for a conduit which has an annularly corrugated outer casing, and in particular to a connector for a coaxial cable with an annularly corrugated outer conductor.
2. Description of Related Art
The use of coaxial cables for the transmission of intelligence by way of the propagation of electromagnetic energy is well known. The present invention is particularly suited to coaxial cables, and in particular to a type of coaxial cable which has an annularly corrugated outer conductor. This type of cable is used in applications where high mechanical strength and the ability to withstand severe environmental conditions are required. Connectors for such cables must not only meet the strength and durability requirements, but must also have a characteristic impedance which matches that of the cable to permit the highest frequency carried by the cable to be transmitted without significant loss.
A variety of connectors suitable for use with coaxial cables having annularly corrugated outer conductors are known. Examples include those disclosed in U.S. Pat. Nos. 5,996,843 (Thommen et al.) 4,824,400 (Spinner), 4,824,401 (Spinner), 4,687,272 (Spinner et al.), 4,046,451 (Juds et al.), 3,910,673 (Stokes), 3,678,446 (Siebelist), 3,291,895 (Van Dyke), and 3,040,288 (Edlen et al.), as well as in German laid-open patent specification No. 2 221 931 (Spinner et al.) and publication entitled Cable Metal RF Feeder System Catalogue, Edition 3.
The present invention has features in common with many of these connectors, each of which is for a coaxial cable having an annularly corrugated outer conductor. For example, such connectors generally use of some type of wedging arrangement for wedging the outer conductor against the connector housing. While many of the previously known arrangements work fine, however, they are generally relatively expensive to implement. For example, the connector shown in the Juds et al. patent includes a clamping member similar in shape to the clamping member of the invention, but in which the clamping member includes longitudinal slots to create spring fingers integral therewith in order to provide the clamping force necessary to ensure good electrical contact. This concept is mechanically acceptable, but it is expensive to cut the necessary slots in the clamping member, and the method requires a secondary machining operation to create the bevelled clamping surface of the clamping member, which tends to raise burrs. The requirement of a bevelled clamping surface on the clamping member is also a disadvantage of the similar device shown in the Edlen et al. patent.
Other examples of relatively complex arrangements, or arrangements which are difficult to assemble due to the need for special tools, include the use of helically-shaped screwed into corrugations of the conduit, as disclosed in the Thommen et al. patent, an elastic plastic ring disposed within a metal connector casing under a compressive force provided by a fastener (the Spinner '401 patent and the German Spinner publication), or a helical spring in a similar arrangement (the Spinner '400 patent), a corrugated pipe nut and screw cap arrangement (the Spinner et al. patent), and a collet and collet clamp assembly to apply a radial force on the outer conductor of the coaxial cable (the Stokes patent).